|
Studies from throughout the world that can help you live longer
November 2002 Table of Contents
1. Transdermal testosterone and cognitive function
Raising bioavailable testosterone levels may be an effective method to improve thinking ability in older men. The levels of bioavailable testosterone for many men older than 50 typically fall below the healthy range for young adult men. In order to determine the effect of testosterone levels on cognition and health perception, transdermal testosterone patches (2-2.5 mg/day) or placebos were given to 44 men (ages 65 to 87) with low bioavailable testosterone levels (under 128 ng/dl) for one year. They also received 500 mg of supplemental calcium and 400 IU of vitamin D. The bioavailable testosterone levels of those in the testosterone group increased from 93 to 162 ng/dl. There was no change in the placebo group. Scores on a short-term memory test improved in both the testosterone and placebo groups. Scores on another test requiring mental flexibility and concentration were slightly improved in the testosterone group. There was a small association with physical health/vitality and testosterone level. Health perception did not change significantly, however this score could have been affected by side effects of skin irritation in both groups. The levels of estrone (a form of estrogen) were slightly increased in the testosterone group (28 to 32 pg/dl). Thus, use of transdermal testosterone in men with low bioavailable testosterone does not impair, and may slightly improve cognitive function. JOURNALS OF GERONTOLOGY SERIES A-BIOLOGICAL SCIENCES AND MEDICAL SCIENCES, 2002, Vol 57, Iss 5, pp M321-M325
2. Tea polyphenols and the cooking of meat
The use of tea may reduce or eliminate the risk of ingesting cancer-causing substances in meat. During the broiling or frying of meat, powerful mutagens are formed. These mutagens cause specific cancers in animals, and studies suggest that they increase the risk of breast and colon cancer in humans. Applying polyphenols from green or black tea to both surfaces of ground beef before cooking inhibits the formation of the mutagens in a dose-related fashion. Thus, using tea polyphenols is a simple and effective procedure to reduce mutagen formation and possibly the risk of cancer. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS, 2002, Vol 516, Iss 1-2, pp 19-22
3. Effect of genistein on tamoxifen in breast cancer
For those women undergoing treatment for breast cancer, the use of genistein may negate the benefits of the anti-estrogen chemo drug, tamoxifen. Genistein is a dietary isoflavone supplement, used increasingly by postmenopausal women with breast cancer. A study investigated its interaction with tamoxifen on the growth of estrogen-dependent breast cancer cells in mice. Administration of an estrogen implant plus 2.5 or 5 mg of tamoxifen suppressed tumor growth in immune compromised mice. However, dietary genistein negated the inhibitory effect of this treatment on tumor growth, lowered estrogen blood levels, and increased the activity of estrogen-responsive genes. Therefore, for postmenopausal women consuming dietary genistein while on tamoxifen therapy for estrogen-responsive breast cancer, caution is suggested. CANCER RESEARCH, 2002, Vol 62, Iss 9, pp 2474-2477
4. Vegetarianism and risk of breast cancer
Being a lifelong vegetarian may be associated with a reduction in the risk of breast cancer. There is an association with a higher intake of vegetables and a lowered cancer risk. A recent study examined 240 South Asian breast cancer cases from 1995 to 1999. A slight reduction in the risk of breast cancer was found in lifelong vegetarians compared to people eating meat. There was no linear trend found in the odds of breast cancer with increasing consumption of meat, but in the top 75% of meat eaters, the risk of breast cancer was higher in women. There was a strong inverse associaton in the risk of breast cancer with increasing pulse, fiber and vegetable intake, with women whose intake of these foods was in the highest 25 percent having half the risk of those in the lowest percentages. There is the possibility that lifelong avoidance of meat may also play a role in lowering risk. The results show that a diet rich in vegetables may protect against breast cancer. INTERNATIONAL JOURNAL OF CANCER, 2002, Vol 99, Iss 2, pp 238-244
5. Safety of herbal ephedra/caffeine for weight loss
The combination of herbal ephedra and caffeine had a beneficial effect on body weight and cholesterol. A six-month study examined the long-term safety and efficacy for weight loss of an herbal Ma Huang (90 mg) and Kola nut (192 mg) supplement in 83 participants who had a body mass index (BMI) of 31.8 kg. The results showed that herbs vs. the placebo decreased a) body weight 5.3 vs. -2.6 kg, b) body fat (-4.3 vs. -2.7 kg), and c) LDL-cholesterol (-8 vs. 0 mg/dl). It increased HDL-cholesterol (+2.7 vs. -0.3 mg/dl). The herbs produced small changes in blood pressure variables (+3 to -5 mmHg) and increased heart rate (+4 vs. -3 bpm). There were no increases in cardiac arrhythmias (abnormal rhythm of the heart beat). The side effects were dry mouth, heartburn and insomnia, but diarrhea decreased. There was no change in irritability, nausea, chest pain and palpitations. Thus, the effect of herbal ephedra/caffeine was to reduce body weight, body fat, and improve blood lipids, with no serious health complications. INTERNATIONAL JOURNAL OF OBESITY, 2002, Vol 26, Iss 5, pp 593-604
6. Mixed vitamin E tocopherols vs. alpha tocopherol vitamin E alone
Mixed vitamin E tocopherols appear to have a stronger effect against lipid peroxidation than vitamin E (alpha-tocopherol) alone. Mixed tocopherols have been found to counteract the development of atherosclerotic cardiovascular disease. However, large amounts of alpha vitamin E have shown only a slight effect or none at all. A study investigated the effects of alpha vitamin E alone compared to mixed vitamin E (gamma, delta and alpha-tocopherol) on lipid peroxidation in human red blood cells induced by hydrogen peroxide. Due to the action of hydrogen peroxide, lipid peroxidation strongly increased and polyunsaturated fatty acids decreased. The culture of red blood cells with mixed tocopherols increased the tocopherol levels in a concentration-dependent manner. Alpha-tocopherol and the tocopherol mixture protected the cells from lipid peroxidation. However, the absorption of gamma and delta-tocopherol compared to alpha-tocopherol was found to be much higher in the cells. The mixture was much more potent than alpha-tocopherol alone. Thus, a combination of vitamin E (gamma, delta and alpha-tocopherol) has a strong inhibitory effect than alpha tocopherol alone on lipid peroxidation in human red blood cells. JOURNAL OF CARDIOVASCULAR PHARMACOLOGY, 2002, Vol 39, Iss 5, pp 714-721
7. Cod liver oil vs. soybean oil in preventing kidney disease
Fish oil and vegetable oil may play roles in helping to prevent nephropathy or kidney disease. A study investigated the effects of cod liver oil (CLO) and soybean oil (SO) on artificially induced kidney disease. CLO significantly reduced urinary albumin excretion and weakened the negative changes in tissue. (Urinary albumin excretion rate is independently related to autonomic kidney disease in type 2 diabetes.) In the mice fed SO, there was an increase of tissue lipid peroxide levels. However, this increase was suppressed in the mice fed CLO. Levels of the major endogenous antioxidant, glutathione (GSH) were also higher in mice fed CLO. After 72 hours, the detoxifying activity of the enzyme, GSH peroxidase in kidney tissue was significantly higher in mice fed CLO. The results suggest that cod liver oil can play an important role in the prevention of kidney disease. LIPIDS, 2002, Vol 37, Iss 4, pp 359-366
8. Green tea and HIV
A study determined the effects of one of the components of green tea, epigallocatechin-3-gallate (EGCG), on HIV infection. Peripheral blood lymphocytes (immune cells) were cultured with either one of two HIV strains (LAI/IIIB or Bal HIV) and increasing concentrations of EGCG. The results showed that the green tea component strongly inhibited the replication of both virus strains, as determined by reverse transcriptase and p24 assays. Thus, the demonstration of antiviral activity in green tea may make it potentially useful in the treatment of HIV virus infections. AIDS, 2002, Vol 16, Iss 6, pp 939-941
9. PUFAs and sudden death after heart attack
Polyunsaturated fatty acids (PUFAs) have shown promise in providing protection from sudden death after a heart attack. A study assessed the benefit of low dose n-3 polyunsaturated fatty acids on mortality in 11,323 survivors of recent heart attack (less than three months prior to the onset of the study). They were given supplements of n-3 PUFAs, vitamin E (300 mg/day), or both, in addition to optimal pharmacological treatment and lifestyle advice. The results showed that total mortality was significantly lowered 41% after three months of treatment with PUFAs. At four months, the reduction in risk of sudden death was 53%. There was a similarly significant, delayed pattern for cardiovascular deaths after six to eight months of treatment. The results of this study are consistent with a wealth of evidence coming from laboratory experiments on isolated heart cells, animals, and clinical studies. The early effect of low-dose n-3 PUFAs on total mortality and sudden death supports the hypothesis that PUFAs can help prevent irregular heartbeat. CIRCULATION, 2002, Vol 105, Iss 16, pp 1897-1903
10. Melatonin reduces memory changes and nerve damage
A study investigated the role of melatonin in induced amnesia in mice. Tests were performed to evaluate their learning and memory functions. There was a significant decrease in their learning and memory ability. The antioxidant activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) were reduced, and TBARS levels (oxidative stress marker) found in brain tissue, were increased. However, the administration of small amounts of melatonin for three months was sufficient to block these changes. The data suggest that elevated free radical generation is involved in accelerating brain aging by reducing antioxidative enzyme activities. The antioxidative activity of melatonin may thus prove effective in combating reduced memory and learning functions associated with aging. JOURNAL OF PINEAL RESEARCH, 2002, Vol 32, Iss 3, pp 173-178
11. Grape seed extract and heart recovery
The consumption of red wine has been shown to have cardioprotective effects that are attributed to the polyphenolic compounds in grapes. A study looked at the effects of red grape seed proanthocyanidins on the recovery of rat hearts after ischemia (a low oxygen state due to inadequate blood flow). In rats treated with 50 mg and 100 mg grapeseed proanthocyanidins/kg for three weeks, the incidence of rapid contraction of the heart muscle was reduced from a starting value of 92%, down to 42% and 25%, respectively. In those treated with 100 mg proanthocyanidins/kg, the recovery of coronary artery flow and aortic flow after 60 min of blood flow restoration was improved by 32% and 98%, respectively. The proanthocyanidins significantly inhibited the formation of oxygen free radicals and reduced their intensity by 75%, compared with the untreated rats. Thus, grape seed proanthocyanidins showed cardioprotective effects by reducing or removing free radicals in the heart tissue after injury due to ischemia-reperfusion. AMERICAN JOURNAL OF CLINICAL NUTRITION, 2002, Vol 75, Iss 5, pp 894-899
12. Lycopene and prostate cancer
The use of lycopene has been shown to have a negative effect on prostate cancer cells. One of the oxidation products of lycopene is acyclo-retinoic acid, a form of all trans-retinoic acid. When cultured with retinoids, acyclo-retinoic acid significantly reduced the growth and viability of two types of prostate cancer cells (PC-3, and DU 145). Thus, the use of lycopene was shown to be beneficial in helping to prevent the development of human prostate cancer. ANTICANCER RESEARCH, 2002, Vol 22, Iss 2A, pp 689-695
13. Vitamin E and prostate cancer
Vitamin E has been shown to inhibit tumor angiogenesis (development of blood vessels) in animals. A study evaluated whether long-term supplementation with vitamin E modified levels of a certain protein involved in angiogenesis. One hundred men not diagnosed with cancer received vitamin E (50 mg daily) and were followed up for four years. The results showed an 11% decrease in levels of this protein in the vitamin E group as compared with a 10% increase in the placebo group. The reduction of this protein and the subsequent inhibition of angiogenesis by vitamin E may help prevent tumor development. Thus, daily supplementation with vitamin E may reduce prostate cancer risk. ANTICANCER RESEARCH, 2002, Vol 22, Iss 1A, pp 375-378
14. Effect of taurine on atherosclerosis
Taurine has been shown to prevent free radical attack and atherosclerosis. In a recent study, mice bred for severe high cholesterol and atherosclerosis were fed a diet containing 2% taurine for three months. Their cholesterol levels were significantly elevated after treatment. The elevation was due to increases in very low-density lipoprotein- (VLDL) and low-density lipoprotein-(LDL) cholesterol. However, despite these effects on blood lipoproteins, taurine reduced the area of arterial lipid accumulation by 28%. There was also a decrease in the size of lesions in the aorta. At the start, blood levels of TBARS (oxidative stress marker) were higher than in mice with normal lipid levels. After three months of taurine in the diet, blood TBAR levels were significantly decreased. Thus, taurine prevents the formation of atherosclerotic lesions, independently of blood cholesterol levels. CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, 2001, Vol 28, Iss 10, pp 809-815
15. Aging and calorie restriction
A study compared profiles from aged animals on a normal diet with those on a low-calorie diet. Specific biological functions were found to be impacted by caloric restriction. The study found that caloric restriction was accompanied by a slowing of the progression of normal, age-related changes in gene transcript levels. Nearly 23% of the genome changed in gene transcript representation on the low-calorie regime. It resulted in the down-regulation of genes primarily involved in cell growth, metabolism and reproduction. Many genes, including those associated with stress response and reproduction, showed age-dependent transcript representation. During the normal aging process, many genes undergo changes in their expression. Age and dietary conditions affect gene activity from many different biological functions and processes. Thus, caloric restriction has been shown to extend life span in animals by slowing down the rate of normal aging. CURRENT BIOLOGY, 2002, Vol 12, Iss 9, pp 712-723
16. Vitamin C and the kidneys
Vitamin C may prevent kidney inflammation caused by phospholipids. (Phospholipids are fats that form the basic structure of cell membranes.) When blood flow is restored (reperfusion) to an organ, injury can occur as an inflammatory response to free radical stress. A study examined whether vitamin C influences the a) platelet-activating factor (PAF) activity of phospholipids, b) kidney inflammatory response, and c) kidney failure. After ischemia and reperfusion in rabbit kidneys, there was a release of PAF. Accompanying the release of the phospholipids was massive DNA oxidation. However, vitamin C was able to weaken these negative DNA oxidative changes and decrease PAF. In rats, administration of vitamin C improved kidney function and structure. The study showed for the first time that phosopholipids are released as part of an oxidative-inflammatory response after ischemia and reperfusion of kidneys, and that their release is significantly reduced by vitamin C. FASEB JOURNAL, 2002, Vol 16, Iss 6, pp NIL_358-NIL_377
17. Raspberry extract and cell proliferation
Raspberry extract has been shown to inhibit cell proliferation. Raspberries are rich in phenolic phytochemicals. The antioxidant activity of the raspberry is directly related to the total amount of phenolics and flavonoids found in it. This investigation found that raspberry extract equivalent to 50 mg of fruit significantly inhibited the proliferation of human liver cancer cells by 89%. It also found that the darkest colored juice showed the highest phytochemical content and vice versa. Thus, raspberries may potentially be beneficial for those with liver cancer. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, 2002, Vol 50, Iss 10, pp 2926-2930
| 
